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Crows, Ravens and Jays

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Crows, Ravens and Jays
Photo © Paul E Tessier / Getty Images.
Crows, ravens and jays (Corvidae) are a group of perching birds that also includes jackdaws, rooks, magpies, nutcrackers, choughs and treepies. In total, there are more than 120 species that belong to the crow family.

Crows, ravens and jays are medium to large birds. The group includes the largest members of the perching birds. Many crows, ravens and jays have large wingspans. They have a robust body, strong feet and sturdy bills. Their nares (nasal openings) are fringed by bristle-like feathers known as rictal bristles. In temperate areas, most members of the group are partly or entirely black, blue, iridescent blue or iridescent purple. Some species, such as the magpies and jays, are more varied in colour. They might have plumage with a mixture of black, white, grey and blue markings.

Members of this group of birds are thought to be highly intelligent, not just among birds but among all animals. Crows and rooks have demonstrated tool making abilities while European magpies have exibited self-awareness in mirror tests.

Many members of the crow family establish and protect territories either during the breeding season or throughout the year. When threatened, some corvids can defend their offspring or territories aggressively and are known to attack large animals such as other birds, dogs or cats. Many species of corvids form social groups and hierarchies for foraging and breeding.

Many species of corvids have flourished in human environments. But while such species have enjoyed healthy populations, a few corvids have experienced declines. Examples of threatened members of the crow family include the Florida scrub jay, the Mariana crow and the New Zealand raven.

Crows and their relatives form strong pair bonds and in some species this association is life-long. In most species, nests are constructed in trees or on rock ledges. Nests are built using twigs, grass and other plant materials. Females lay between 3 and 10 eggs and young fledge after about 10 days.

Size:

The largest member of the crow family is the common raven which grows to more than 26 inches in length and weighs 3 pounds. The smallest member of the crow family is the dwarf jay which grows to about 8 inches and weighs little more than an ounce.

Habitat:

Crows, ravens and jays have a nearly-worldwide distribution. They are absent from only the southern tip of South America and the polar regions. The group is most diverse in tropical regions of Central America, South America, Asia and Europe. Most members of the crow family do not migrate although when food shortages occur, populations do relocate.

Classification:

Animals > Chordates > Birds > Perching Birds > Crows, Ravens and Jays

The crows, ravens and jays are divided into about a dozen subgroups, some of which include New World jays, grey jays, azure-winged magpies, Holarctic magpies, Stresemann's bushcrow, piapiac, true crows, nutcrackers, Old World jays, Oriental magpies, treepies and choughs.

Evolution:

The crow family is thought to have originated in Australia and spread throughout the world. The closest relatives of the crows, ravens and jays are thought to be the birds of paradise and shrikes. There remains considerable ambiguity regarding the exact lineages and their relationships within the crow family. The earliest members of the crow family date back about 17 million years ago to the middle MIocene. Known fossils include Miocorvus, Miocitta, Miopica and Henocitta.

Diet:

Crows, ravens and jays feed a variety of foods including small mammals, birds, invertebrates as well as fruits, seeds and berries. Some members of the crow family feed on insects such as grasshoppers while others feed on carrion.
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